1. Field of the Invention
The present invention is directed to a method for the operation of a diagnostic magnetic resonance apparatus having a number of local antennas.
2. Description of the Prior Art
In diagnostic magnetic resonance apparatus, local antennas are utilized for improving the signal-to-noise ratio, and thus improving the imaging quality. The positioning of the local antennas applied to a patient in the magnetic resonance apparatus has conventionally ensued with the assistance of a light sighting means, which marks a region that has a defined or known spacing from the magnetic field center or from the center of the imaging region. To that end, a center of the local antenna to be applied is first brought into coincidence with a light indicator generated by the light-sighting means. This can ensue by appropriate placement of the patient on a patient support or by a corresponding positioning of the patient support with the patient thereon. Subsequently, the patient together with the patient support is moved by the defined distance into the imaging region of the magnetic resonance apparatus. In many magnetic resonance apparatuses, the position acquisition is limited to a single coordinate direction, namely the direction of the displacement path of the patient support. It is not possible to communicate the positions of a number of simultaneously employed local antennas to the magnetic resonance apparatus.
German PS 196 53 535, corresponding to U.S. Pat. No. 5,936,406, discloses a method for position determination, wherein spatially-encoded magnetic resonance signals are received with a whole body antenna as well as with the local antennas to be applied. Spatially resolved image information in the form of intensity values are generated from the received magnetic resonance signals. After normalization, the coordinate value that belongs to the highest normalized intensity value is identified, and this indicates the position of the local antenna in the coordinate direction. The position of each local antenna can then be defined and, as needed, communicated to the device controller.
European Application 0 374 994 discloses an antenna system that has a first sub-system in order to generate an overall image and a second sub-system having a number of local antennas. Markers are allocated to the local antennas, these markers being capable of being made visible in an image presentation. The markers allow an identification of the individual local antennas. The antennas allocated to the identified markers can be activated via a control panel. A disadvantage of this system is that the imaged markers are visible in every image and can be disturbing.